Practice Problems

Basic Stack Operations:

• Valid Parentheses
• Implement Stack using Queues
• Reverse a string using Stack
• Backspace String Compare
• Baseball Game
• Reverse a string using Stack

Monotonic Stack:

• Next Greater Element I
• Next Greater Element II
• Help Classmates
• Daily Temperatures
• Trapping Rain Water
• Largest Rectangle in Histogram

Stack with Extra Operations:

• Min Stack
• Max Stack
• Online Stock Span
• Sum of Subarray Minimums
• Maximum Frequency Stack

Stack with Recursion or DFS:

• Simplify Path
• Basic Calculator II
• Decode String
• Expression Add Operators
• Basic Calculator

Infix/Prefix/Postfix Expressions:

• Evaluate Reverse Polish Notation
• Infix to Postfix Conversion

Stack with Backtracking:

• Remove K Digits
• 132 Pattern
• Asteroid Collision
• Smallest Subsequence of Distinct Characters

Stack in Tree Traversals:

• Binary Tree Inorder Traversal
• Binary Tree Preorder Traversal
• Iterative Postorder Traversal
• Binary Search Tree Iterator
• Flatten Binary Tree to Linked List